The story tells the adventures of the wandering sailor Ishmael and his voyage on the whaleship Pequod, commanded by Captain Ahab. Ishmael soon learns that Ahab seeks one specific whale, Moby Dick, a white whale of tremendous size and ferocity. Comparatively few whaleships know of Moby Dick, and fewer yet have encountered him. In a previous encounter, the whale destroyed Ahab's boat and bit off his leg. Ahab intends to take revenge.